Windows 8.1's RTM, which Microsoft announced on Tuesday, has leaked to file-sharing sites, according to numerous forum postings and blog reports.

Leaks of unreleased Microsoft products, especially Windows, are commonplace, and as in this case, often occur just hours or days after the Redmond, Wash. company ships code to its partners.

Microsoft may have contributed to the interest in Windows 8.1 RTM -- a term that represents "release to manufacturers" -- because of a change in a long-standing policy that gave developers and IT professionals access to the official code weeks before the general public.

The leaked builds of Windows 8.1 RTM may have originated in China -- home of most of the companies that build the world's personal computers and tablets -- because a Chinese-language edition was the first to appear.

Within a short time, however, English editions of the RTM also popped up on file-sharing websites.

While at one time Microsoft tried to stamp out such leaks, it long ago gave up and switched to warning users that unauthorized builds, including counterfeits circulating long after a product's release, often contained malware.

Microsoft will officially launch Windows 8.1 on Oct. 17 in the U.S., the first date that current Windows 8 users can retrieve the free update from the Windows Store. Hardware that relies on Windows 8.1, as well as retail copies of the operating system, will go on sale Oct. 18.

Microsoft has not revealed the price of the retail copies of Windows 8.1 aimed at customers still running Windows XP, Vista or Windows 7.

The company has enraged developers with its decision to not publish the RTM on MSDN (Microsoft Developer Network) and TechNet, the subscription-only sites aimed at developers and enterprise IT personnel, respectively. Previously, those subscribers could download RTM builds about two weeks after computer makers received the code, and weeks before the software went on sale.

Microsoft said the change was necessary because RTM is not a finished, polished product, but will continue to receive fix bugs between now and October. MSDN and TechNet subscribers must wait like everyone else for the official debut.

"How on earth can a developer deliver a quality app and not be able to test in on production grade code from Microsoft?" asked someone identified as "mirronelli" in a comment appended to a Microsoft blog that advised developers to test their work against the two-month old Windows 8.1 preview.

Some were even angrier.

"This is insanity. What possible justification could you have for not releasing the RTM code to developers ahead of schedule?" wondered "sognibene" today. "You want to know why you don't have apps in the [Windows Store] without paying developers to make them? THIS TYPE OF NONSENSE IS WHY!!!"